Robust error handling in downloading code

youtube-dl

@@ -930,6 +930,7 @@ class FileDownloader(object):
 			if stream is None:
 				try:
 					(stream, tmpfilename) = sanitize_open(tmpfilename, open_mode)
+					assert stream is not None
 					filename = self.undo_temp_name(tmpfilename)
 					self.report_destination(filename)
 				except (OSError, IOError), err:
@@ -951,6 +952,9 @@ class FileDownloader(object):
 			# Apply rate limit
 			self.slow_down(start, byte_counter - resume_len)
 
+		if stream is None:
+			self.trouble(u'\nERROR: Did not get any data blocks')
+			return False
 		stream.close()
 		self.report_finish()
 		if data_len is not None and byte_counter != data_len: